Field of the Invention
The invention is directed to a semiconductor technology. More particularly, the invention is directed to an active region structure and a forming method thereof.
Description of Related Art
In recent years, electronic products are generally designed with multifunction and fast processing capability. In order to increase the processing capability, a computer system or a multifunctional electronic product, for example, requires a dynamic random access memory (DRAM) with large capacity. For increasing the memory capacity, a size of memory cells of a memory has to be reduced; however, other problems arise therefrom after the size of the memory cells are significantly reduced, which lead to instability or damage to the operation of the memory cells.
In a semiconductor device, an active layer unit is generally defined on a substrate and employed as a base that a required device structure is formed thereon. Thus, as the active layer unit on the substrate is employed as a base of the device, a size, a shape and a position of the device are determined based thereon. The active layer unit is also referred to as a device cell hereinafter.
Taking memory cells of a memory as an example, a plurality of memory cells are regularly arranged in a predetermined device region to form an array. A device cell eventually forms a memory cell. Moreover, for the memory cells capable of being operated, some peripheral circuits are provided in the periphery of the memory cells to control the memory cells. The peripheral circuits are also formed based on a peripheral active region.
Therefore, under the need of dramatically reducing the dimension of the semiconductor device, how to design the device structure for maintaining them in normal operation is one of the subjects to be considered.